[sr-dev] RTPengine docs

[Olle E. Johansson]

Hi!

I took the liberty of adding result code to rtpengine_offer. It was used in the example, but not stated in the README.

When generating a new README a lot of new stuff showed up that wasn’t generated from the XML before. I hope I
did not reveal anything secret :-)

I humbly suggest that you create a different result code, like -2, if there are no RTPengines available. Right now
a -1 indicates a lot of different errors.

I would also like to suggest PRACK to the methods that can be approved to carry an SDP, as it is rather commonly
used.

Thanks.

/O